Wind power is one of ideal green energies. It is inexhaustible, particularly in the case of generating electricity. The primary working principle of electricity generation through wind power is to utilize wind power to drive wind-driven rotors, such as the blades of a windmill, which then in turn drive the rotation of an electrical generator, thereby transforming the mechanical energy into electrical energy. Although the principle of electricity generation through wind power is extremely simple, its application in actual processes is very limited. Current statistical data shows that, even in a relatively developed wind power generating country such as the United States, wind power generation only makes up for a very small proportion of the total amount of electricity generated. The most significant reason for this is that wind power is an extremely unstable energy source. For example, the 65-kilowatt wind power generation equipment used in California's Altamont Pass, a concentrated wind power site in the United States, have 48-foot diameter rotors and a designed wind speed of 35 mph. Their average cost per kilowatt hour is approximately US$0.05. If, however, this wind power generation equipment were installed in any other region, there would be changes in the triangular relationship between the decreased effective wind speed, the cost effectiveness, and the wind speed. If it is used in an area of distribution type wind power, the technical and economic instruction standards would decrease to a level that would make it difficult to meet the consumer's needs. When wind power device being used in the Xilin pasture lands of Inner Mongolia, for example, the average wind speed in July each year drops to 6.3 mph, and the original 65 kilowatt power rating equipment drops to 0.4 kilowatts. Actually, in the areas with the richest wind power resources in China, the average annual wind speed is only 10 mph. Because China is a country with limited wind power resources, the existing wind power generation equipment described above are not suited in this region.
In summary, the main reason that wind power generation cannot be commercially adopted over a large area is that the design parameters for each wind power generation device are determined according to general environmental conditions. These parameters often are based on the installation environment of the wind power generation equipment—i.e., the wind power resources—and the equipment are designed with a predetermined objective after undergoing a great deal of aerodynamics testing. For these reasons, when the wind power generation equipment leaves the factory, its design parameters cannot be randomly adjusted in accordance with the actual working conditions or, if they can, the range of adjustment is extremely narrow. Because the parameters of wind power resources cannot be fixed, the design parameters of wind power generation equipment cannot always be matched with the wind power resource conditions even through meticulous design. When the conditions are not matched, the power generation efficiency is extremely low. For example, manufacturers usually design small-size wind power generation equipment for a wind speed of greater than 11 m/s, but the average wind speed in actual operating environments of small-size wind power machinery can only reach 3˜5 m/s. For this reason, the actual power output often can only reach one tenth of the rated power output.
In addition, the more advanced wind power generation equipment currently available in the world use the type of propeller rotor or axial flow rotor used in aerospace technology. Testing has shown that propeller rotors and axial flow type rotors operate optimally under conditions of high-speed airflow. In general, the diameter of an airplane propeller rotor does not exceed 3 meters, but the power output can reach 600˜3,000 kilowatts. Although the diameter of a helicopter rotor is somewhat bigger, the operating speed of its blade tip position generally reaches over Mach 0.5. Therefore, use of these types of aerospace technology application propeller rotor structures in wind power generation areas with lower wind speeds (general operating wind speeds of only about 5˜10 m/s) is far out of the aerodynamically appropriate range of usage for a propeller rotor. Also, it is very difficult, to lower the manufacturing costs. With its high manufacturing & usage costs and low wind power efficiency, its technological targets make it very difficult for wide distribution of wind power resources and for the products to reach a viable usage level. This type of wind power generation equipment, therefore, can only be used at a wind power generation site with relatively rich wind power resources. Essentially, the application of propeller rotor technology in the realm of wind power generation has been a misleading direction in its technological development. Not only is it disadvantageous to the utilization of wind power resources, but also it has prevented other technological advancement from establishing a large user base.
The earliest human use of wind power stems from popular windmills. People used windmills for irrigation and milling, basically turning wind power into mechanical energy, such as the widely known Dutch windmills. In order to increase the wind power conversion efficiency of windmills, these locally used windmills needed to be designed and installed in accordance with the local wind conditions, and they needed to be individually adjusted so as to achieve the highest wind power/mechanical power conversion efficiency. Individual adjustment methods, however, were not suited to large-scale production of windmills, and the additional adjustment increased the manufacturing and usage costs of the windmills. Even more importantly, once a windmill is installed, its structure is fixed, and it is no longer adjustable. In keeping with the electrical energy demands of modern man, people began to use windmills to generate electricity. Because these popular windmills could not be randomly adjusted according to the wind conditions during operation, their conversion efficiency was similarly compromised. Current use of windmills to generate electricity, therefore, is not fully developed and widely adopted.
Under general conditions, windmills or the propellers in wind power device inventions all increase the torque of the wind power rotors by increasing the diameter. When a wind power rotor with an excessively large diameter encounters strong winds, however, the propeller blades can be easily damaged. Materials such as high strength carbon fibre materials are usually used to manufacture the blades of current wind power generation devices, and the manufacturing costs are extremely high as a result.